The last step to finish your quilt is binding.
First, you need to trim up all of the sides, making sure you have a nice straight line where the top, batting, and backing come together. To do this, use your cutting mat, rotary blade, and a template/ruler for a straight edge.
See how nice and clean that looks.
If you have never binded a quilt before, I would suggest this tutorial from Mollyflanders.blogspot.com.
You can buy pre-made binding from the craft/fabric store, but I like to make my own.
When machine binding, I recommend sewing the binding to the back side of the quilt first.
Then flip the quilt over and complete the binding.
And...drum roll please....TA-DA!
And the back of the quilt...
Optional step: Labeling